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Re: Sony A7R III Dynamic range at 14.7 Evs

Matt Grum wrote:
leetmode wrote:
IMO, rounding up 14.7 to 15 isn't really that liberal. Rounding up 14.8 to 16 is... but what do I know.

You can claim any figure you like for DR since there's no standard to measure it by.

nehemiahphoto wrote:
Still wondering if the A7r3 is this good at ISO 100, why they didnít add a real ISO64...they would have passed the d850.

Because you can't just add a real ISO 64 (except by glueing an ND filter to the sensor). To do it in a way that increases DR for the same pixel size you have to increase the full well capacity, but it's hard to do this without increasing read noise, which hurts DR.

Yes, I am aware the sensor has deeper wells allowing it to collect more light, but is the gain in DR not worth the noise added? Otherwise why would Nikon be doing this?

nehemiahphoto wrote
The A7r2 was tested pre fw allowing for uncompressed raw, giving a bump in DR. Others may know better, but youíre really getting about a .4 stop boost I think.

Compressed RAW makes a very small difference in DR, the delta encoding only affects pixels on the border between very bright and very dark areas. The only other effect of compression in the shadows is a drop from 14 bits to 13 bits, which increases quantisation noise but only very slightly.

Aztatlan wrote:
The uncompressed RAW thing does explain it, though.

I don't think it does, a better explanation I think is that there's a difference between the quantitative shadow noise (used to produce DR graphs) and qualitative shadow noise which is what you see in the dpreview comparison images.

Nov 28, 2017 at 10:00 PM

  Previous versions of nehemiahphoto's message #14269739 « Sony A7R III Dynamic range at 14.7 Evs »